Two simple propositions, taken from Vedantic philosophy, summarize the whole of truth and the way to attain it. One is from the verse 2:16 of Bhagavad Gita and the other is from Upanishads:
1) The Real cannot not be; the unreal cannot be.
2) That which begins must end.
We needed nothing more if we were intuitive rather than discursive and fond of intellectual currencies, beliefs. All religions and mythologies express the same thing, and all philosophies and sciences strive to grasp it.
These two statements, complementary in nature, must be realized. To go a little in depth we can add the following:
If the Real cannot not be, then all things that begin and end are unreal though apparent. And that which is unreal does not exist whether it is apparent or not; it can exist only as appearance.
Reflecting on things that begin and end we see that there is nothing that is excluded except the one for whom things begin and end. Standing here I see that my body is totally different from the body with which I was born; all those cells have already died and these too will die. Thus, I cannot be the body; because if I were I could not possibly say that I am the body! Change is meaningful only against an unchanging background. Change which means distinction and differentiation is possible only for an agent who remains the same throughout these changes so to be able to perceive them as change as such. I can see two different things if and only if the eye that sees the first is the same eye that sees the second so to establish their difference.
Also I cannot be the mind since all the contents, thoughts and emotions, change overtime, more so overnight; they begin and end while I subsist. I am the same “I” that I was when I was 5 while nothing about it, including body mind, emotions and personality, remains the same; they all begin and end while the “I” remains the “I.” This enduing I has no personality, because personality, the collection of thoughts and emotions and inclinations, changes, it begins and ends, while the “I” subsists. The “I” is the bearer of personality, the substratum upon which personality is superimposed. Thus, personality too cannot be real; it is an artifact of the impermanent flux we call the world.
Everything begins and ends except the “I” for whom things begin and end, the witness “I” or the I-witness if you will. The “I” cannot not be. When I, as this I, say that I die I really mean the personality and its ego, its thoughts and emotions and body; but these were not real to begin with since they always began and ended even while this “I” is said to be living. The “I” still remains in the world but only perceived as this I or that I, as you or someone else. It is essentially the I in all of us that is the Real component, for it cannot not be. Notice that if I say “but there was a time when no one was but the world was” it is because I first am. This world that I claim to exist without me is the world known in and through the I; it is the world in I and not I in the world. It is the world in the eye of the I. Without the “I” I cannot posit the independent existence of the world, hence I must not only precede the world but also subsist in it. Notice that whenever and wherever the “I” is, the world too is; and whenever and wherever the “I” is not, the world too is not.
The subsisting “I” is the Real and also inexpressible One. To say anything about it is to hide it because all sayings and thoughts begin and end; they cannot be Real. The “I” is that which expresses; it cannot be pronounced, for it is He who must do the pronouncing. The Immortal One is the Inexpressible.
My friend, this “I” who is the immortal One and no one’s I is nothing but the I of God which is the same as the eye of God, for God is pure seeing, pure Being, pure bliss. Realize this and be free of all conditioning: You were never born; how can you ever die? How can you not be!